I am trying to decide how to proceed with a brake problem. Here is where things stand:

1. I replaced warped rotors with Zimmerman cross-drilled, and used new Volvo pads. Pulsing stopped immediately.
2. Within a week or two the pulsing started again, and is worse after the car has been driven for longer periods.

I realize this could be excessive runout on the rotors, and that trying different positions for the rotors might help, but I need to use a dial indicator to measure runout.

Where should I buy a dial indicator and for how much? What kind should I look for?

I am also aware that rotor warping is usually caused by sticking calipers, and in my 1991 745T I have the later "jumbo" single-piston sliding caliper. Would lubing the guide pins make a difference? Or should I replace the guide pins? I am not going to attempt to rebuild my calipers, so would it be better to jump ahead to buying rebuilt calipers and just replace them and buy new rotors at the same time?

I am trying to keep from wasting time trying many different things, but I don't want to spend too much money if I don't have to. Thanks in advance for the advice.
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Darius in Albany NY '86 744 GLE (175K, given to my mother-in-law); '91 745 Turbo (167K-my 'Little Red Wagon')